I'm not sure whether this answers your question as I do not know the precise weights. But I can tell you that the payload of the 3 litre is reduced by 67kg as compared to the 2.3 litre engine.
The 3 litre engine is fantastic but my advice would be to avoid buying the manual gearbox version. It judders and, unlike the 2.3, there is no fix and Fiat deny the existence of the problem. Look on the outandaboutlive and MotorhomeFacts websites for confirmation. The Comfortmatic (automatic) gearbox (which is an option for 3 litre engined models only) is, however, brilliant but you may have a long wait to get one. I waited 5 months for mine but it was worth it.